1. Field of the Invention
The present invention relate to an ink cartridge for use in an ink jet painter, and more particularly to an ink cartridge provided with an ink reervoir filled with an ink permeated material, such as ink containing porous material.
2. Description of the Related Art
Typically, ink jet printers are provided with a recording unit, a recording medium feeding unit for feeding a recording medium, and a carriage unit for reciprocally moving the recording unit in the widthwise dimension of the recording medium. The recording unit includes an ink jet type print head and an ink cartridge detachably mounted on the recording unit for supplying ink to the print head. The recording medium feeding unit includes a platen roller for feeding the recording medium past the recording unit in a direction perpendicular to the direction in which the recording unit reciprocally moves. The carriage unit includes a carriage for mounting ttie recording unit thereon. The carriage slidably movably supported on a guide rod extending in parallel with the axial direction of the platen roller. The carriage is reciprocally moved back and fortt along the guide rod by a belt stretched between a drive pulley driven by a motor and a driver pulley.
As disclosed in Japanese Laid-Open Patent Publication (Kokai) No. HEI-7-32603, the ink cartridge is formed with not only an ink introduction port for supplying ink from an ink reservoir to the print head but also a communication hole open to atmosphere, so that the internal space of the ink cartridge is held at the atmospheric pressure and thus ink supply from the ink reservoir to the print head can be smoothly performed. When such an atmosphere communication hole is provided, it is required that air be prevented from freely moving through the communication hole in order to prevent ink evaporation. To this end, it has been a general practice to connect the ink reservoir and atmosphere with a communication path of a labyrinthine structure.
One such example is shown in FIG. 1 wherein a groove c of a crank or labyrinthine structure is formed on the top surface of a lid b attached to an ink cartridge. One end of the groove c is in communication with the internal space of the ink cartridge, i.e., ink reservoir. A seal member d is bonded or thermally adhered to cover the groove c while exposing the other and of the groove in atmosphere, thereby bringing the ink reservoir into communication with atmosphere.
Another example is shown in FIG. 2. A large-diameter attachment hole f is formed in the cartridge body e and an attachment member g is fitted into the attachment hole f The attachment member g is formed with apertures. The attachment hole r and the attachment member g in combination provide an atmosphere communication channel of labyrinthine structure. Hence, the internal space of the ink cartridge is drought into communication with atmosphere.
However, the conventional structures as described above increase the number of components required for forming the atmosphere communication path, such as seal member d or attachment member g. This increases the number of manufacturing steps and manufacturing cost.